Dividing groove forming device, and dividing groove forming method

ABSTRACT

A dividing groove forming device includes: a first cutter including a plurality of first rotary blades; a second cutter including a plurality of second rotary blades; a first rotation drive unit for rotationally driving the first cutter; a second rotation drive unit for rotationally driving the second cutter; a cutter support unit; and a phase adjustment unit. The cutter support unit supports the first cutter and the second cutter such that the first and second cutters are radially opposed to each other so that rotation axes of the first and second cutters are parallel to each other. The phase adjustment unit adjusts a phase of at least one of the first cutter and the second cutter such that the first rotary blades and the second rotary blades are opposed to each other in an opposing area in which the first cutter and the second cutter are opposed to each other.

TECHNICAL FIELD

The present invention relates to a dividing groove forming device and a dividing groove forming method for forming dividing grooves for dividing a substrate at corresponding positions on one surface and the other surface of the substrate.

BACKGROUND ART

Heretofore, the following method is known as a method for manufacturing a substrate of an electric device and the like. Specifically, a plurality of substrates are collectively built in one substrate. Dividing grooves are formed from front and back surfaces between unit substrates in the substrate. The substrate is divided into a plurality of unit substrates by the dividing grooves. Patent Literature 1 discloses an example of a dividing groove forming device used for such a substrate manufacturing method. This dividing groove forming device includes two cutters each including a plurality of rotary blades.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2012-86353

In the related art disclosed in Patent Literature 1, the positional relationship between the rotary blades of the two cutters was not taken into consideration at all. Accordingly, there is a possibility that, in an opposing area in which the two cutters are opposed to each other, the positions of the rotary blades can deviate from their opposed oppositions in most of a rotational driving period. Therefore, there is a possibility that a waviness phenomenon occurs on the substrate.

The waviness phenomenon will be described in detail later. FIG. 6 is a front view illustrating a positional relationship between a first rotary blade 2 a and a second rotary blade 3 a in a dividing groove forming device 1 of the related art which is the same type of the above-mentioned related art. Referring to FIG. 6, the first rotary blade 2 a of a first cutter 2 and the second rotary blade 3 a of a second cutter 3 deviate from their opposing positions. Accordingly, a first portion 4 a of a substrate 4 with which the first rotary blade 2 a is brought into contact is pressed downward and deformed. A second portion 4 b of the substrate 4 with which the second rotary blade 3 a is brought into contact is pressed upward and deformed. As a result, a waviness phenomenon occurs on the substrate 4, so that the depth of the dividing grooves formed in the first rotary blade 2 a and the second rotary blade 3 a becomes non-uniform. Further, if the waviness width increases, the dividing grooves themselves may not be formed, or the dividing grooves may penetrate through the substrate 4. If the dividing grooves penetrate through the substrate 4, the strength of the substrate 4 is considerably lowered, so that a malfunction occurs in post processing, and at worst, the substrate may crack during formation of the dividing grooves.

SUMMARY OF INVENTION

The present invention has been made in view of the above-mentioned problems. An object of the present invention is to provide a dividing groove forming device and a dividing groove forming method which are capable of forming dividing grooves accurately at a constant depth.

In order to achieve the above-described object, a feature of a dividing groove forming device according to the present invention is that the dividing groove forming device is for simultaneously forming a first dividing groove and a second dividing groove for dividing a substrate, the first dividing groove and the second dividing groove being respectively formed at corresponding positions on one surface and the other surface of the substrate, and the dividing groove forming device includes: a first cutter for forming the first dividing groove, the first cutter including a plurality of first rotary blades; a second cutter for forming the second dividing groove, the second cutter including a plurality of second rotary blades; a first rotation drive unit for rotationally driving the first cutter; a second rotation drive unit for rotationally driving the second cutter; a cutter support unit for supporting the first cutter and the second cutter in such a manner that the first cutter and the second cutter are radially opposed to each other so that rotation axes of the first cutter and the second cutter are parallel to each other; and a phase adjustment unit for adjusting a phase of at least one of the first cutter and the second cutter in such a manner that the first rotary blades and the second rotary blades are opposed to each other in an opposing area in which the first cutter and the second cutter are opposed to each other.

In this structure, the first rotary blades and the second rotary blades are opposed to each other in an opposing area in which the first cutter and the second cutter are opposed to each other. Accordingly, a waviness phenomenon can be prevented from occurring on the substrate when the first dividing groove and the second dividing groove are formed, and the first dividing groove and the second dividing groove can be formed accurately at a constant depth.

Another feature of the present invention is configured as follows. The dividing groove forming device further includes an X-direction drive unit for causing the first cutter and the second cutter to move relatively to the substrate in a direction in which the first dividing groove and the second dividing groove extend.

In this structure, the X-direction drive unit enables the first cutter and the second cutter to move relatively to the substrate. Therefore, the first dividing groove and the second dividing groove can be smoothly formed.

Another feature of the present invention is configured as follows. The first rotation drive unit includes a first motor, the second rotation drive unit includes a second motor, the phase adjustment unit includes a control unit for controlling at least one of the first motor and the second motor, and the control unit controls at least one of the first motor and the second motor in such a manner that the first rotary blades and the second rotary blades are opposed to each other in the opposing area.

In this structure, at least one of the first motor and the second motor is controlled by the control unit. Therefore, the phase of at least one of the first cutter and the second cutter can be adjusted rapidly and accurately.

Another feature of the present invention is configured as follows. The plurality of first rotary blades are the same in number as the plurality of second rotary blades, and the plurality of first rotary blades and the plurality of second rotary blades are provided at the same pitch angle, the phase adjustment unit includes a phase detection part for detecting a phase of each of the first cutter and the second cutter, and the control unit controls at least one of the first motor and the second motor in such a manner that a difference between the phase of the first cutter and the phase of the second cutter is equal to an integral multiple of the pitch angle.

In this structure, the plurality of first rotary blades are the same in number as the plurality of second rotary blades, and the first rotary blades and the second rotary blades are provided at the same pitch angle. Accordingly, the first rotary blades and the second rotary blades can be opposed to each other in the opposing area, as long as a difference between the phase of the first cutter and the phase of the second cutter is equal to an integral multiple of the pitch angle. Therefore, the first rotary blades and the second rotary blades can be easily opposed to each other in the opposing area only by controlling at least one of the first motor and the second motor so that the phase difference becomes equal to an integral multiple of the pitch angle.

In order to achieve the above-described object, a feature of a dividing groove forming method according to the present invention is that the dividing groove forming method is for simultaneously forming a first dividing groove and a second dividing groove for dividing a substrate at corresponding positions on one surface and the other surface of the substrate, and the dividing groove forming method includes: (a) arranging a first cutter for forming the first dividing groove and a second cutter for forming the second dividing groove in such a manner that the first cutter and the second cutter are radially opposed to each other so that rotation axes of the first cutter and the second cutter are parallel to each other, the first cutter including a plurality of first rotary blades, the second cutter including a plurality of second rotary blades; (b) rotating the first cutter and the second cutter in such a manner that the first rotary blades and the second rotary blades are opposed to each other in an opposing area in which the first cutter and the second cutter are opposed to each other; and (c) forming the first dividing groove and the second dividing groove by causing the first cutter and the second cutter to move relatively to the substrate in a direction in which the first dividing groove and the second dividing groove extend.

In this method, the first rotary blades and the second rotary blades are opposed to each other in an opposing area in which the first cutter and the second cutter are opposed to each other. Accordingly, a waviness phenomenon can be prevented from occurring on the substrate when the first dividing groove and the second dividing groove are formed, and the first dividing groove and the second dividing groove can be formed accurately at a constant depth.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view illustrating a structure of a dividing groove forming device according to one embodiment of the present invention;

FIG. 2 is a block diagram illustrating the structure of the dividing groove forming device according to one embodiment of the present invention;

FIG. 3 is a perspective view illustrating a process for forming a dividing groove in a substrate;

FIG. 4 is an enlarged front view illustrating a state where first rotary blades and second rotary blades are opposed to each other;

FIG. 5 is a flowchart illustrating each process of a dividing groove forming method according to one embodiment of the present invention; and

FIG. 6 is a front view illustrating a positional relationship between first rotary blades and second rotary blades in a dividing groove forming device of related art.

DESCRIPTION OF EMBODIMENTS

Embodiments of a dividing groove device and a dividing groove forming method according to the present invention will be described below with reference to the drawings.

[Dividing Groove Forming Device]

FIG. 1 is a front view illustrating a structure of a dividing groove forming device 10 according to one embodiment of the present invention. FIG. 2 is a block diagram illustrating the structure of the dividing groove forming device 10. FIG. 3 is a perspective view illustrating a process for forming dividing grooves 14 and 16 in a substrate 12. As illustrated in FIG. 3, a direction in which the dividing grooves 14 and 16 extend in a horizontal plane is hereinafter referred to as an X-direction; a vertical direction is hereinafter referred to as a Z-direction; and a direction perpendicular to each of the X-direction and the Z-direction is hereinafter referred to as a Y-direction.

As illustrated in FIG. 2, the dividing groove forming device 10 is used to simultaneously form the first dividing groove 14 and the second dividing groove 16 for dividing the substrate 12 at corresponding positions on one surface 12 a and the other surface 12 b of the substrate 12. As illustrated in FIG. 3, the substrate 12 used in this embodiment is a collective substrate which has a small thickness (a thickness of about 0.3 to 0.4 mm) and in which a plurality of (nine in this embodiment) unit substrates 18 that are used for an electric device (e.g., a cellular phone) and the like are built. The first dividing groove 14 and the second dividing groove 16 have a depth of about 0.1 mm and are formed into a V-shape. Note that the thickness of the substrate 12 and the depth of each of the first dividing groove 14 and the second dividing groove 16 are not limited to those of this embodiment.

As illustrated in FIG. 1, the dividing groove forming device 10 includes a disk-shaped first cutter 20, a disk-shaped second cutter 22, a rotating table 24, and a work chuck 26.

As illustrated in FIG. 1, the first cutter 20 includes a disk-shaped base metal 30 and a plurality of (20 in this embodiment) first rotary blades 32 which are provided at an outer periphery of the base metal 30. As illustrated in FIG. 2, a through-hole 36 through which a rotating shaft 34 a of a first motor 34, which is described later, is inserted is formed at a central part of the base metal 30. In a part of the base metal 30 in the vicinity of the through-hole 36, a plurality of (four in this embodiment) through-holes 40 through which bolts 38 are respectively inserted are formed. In a part of the base metal 30 in the vicinity of the through-holes 40, at least one (one in this embodiment) through-hole 44 through which a positioning pin 42 is inserted is formed.

The first rotary blades 32 illustrated in FIG. 1 are cutting blades for forming the first dividing groove 14 (FIG. 2) by cutting the substrate 12. The plurality of first rotary blades 32 are provided at regular intervals (at angular intervals of 18 degrees in this embodiment) at the outer periphery of the base metal 30. In this embodiment, the first cutter 20 is structured to rotate clockwise in a front view, and each first rotary blade 32 is provided so as to face forward in the clockwise direction.

As illustrated in FIG. 1, the second cutter 22 includes a disk-shaped base metal 50 and a plurality of (20 in this embodiment) second rotary blades 52 which are provided at an outer periphery of the base metal 50. As illustrated in FIG. 2, a through-hole 56 through which a rotating shaft 54 a of a second motor 54, which is describer later, is inserted is formed at a central part of the base metal 50. In a part of the base metal 50 in the vicinity of the through-hole 56, a plurality of (four in this embodiment) through-holes 60 through which bolts 58 are respectively inserted are formed. In a part of the base metal 50 in the vicinity of the through-holes 60, at least one (one in this embodiment) through-hole 64 through which a positioning pin 62 is inserted is formed.

The second rotary blades 52 illustrated in FIG. 1 are cutting blades for forming the second dividing groove 16 (FIG. 2) by cutting the substrate 12. The plurality of second rotary blades 52 are provided at regular intervals (at angular intervals of 18 degrees in this embodiment) at the outer periphery of the base metal 50. In this embodiment, the second cutter 22 is structured to rotate counterclockwise in a front view, and each second rotary blade 52 is provided so as to face forward in the counterclockwise direction.

As illustrated in FIG. 1, the rotating table 24 supports the substrate 12 in the process for forming the first dividing groove 14 and the second dividing groove 16 (FIG. 2). The rotating table 24 is provided with a table rotation drive unit 68 (FIG. 2) for changing the direction of the rotating table between the X-direction and the Y-direction. Accordingly, even when the substrate 12 supported by the rotating table 24 is cut along a dividing line L1 and a dividing line L2, which are perpendicular to each other, the first cutter 20 and the second cutter 22 may be caused to move only in one of the X-direction and the Y-direction (only in the X-direction in this embodiment). The table rotation drive unit 68 includes a servo motor (not shown). As illustrated in FIG. 2, the table rotation drive unit 68 is electrically connected to a control unit 70. The servo motor (not shown) and the like of the table rotation drive unit 68 are controlled based on a control signal supplied from the control unit 70.

As illustrated in FIG. 1, the work chuck 26 is used to fix the substrate 12 to the rotating table 24. The work chuck 26 of this embodiment is a vacuum chuck that is structured to be able to adsorb the substrate 12 with a negative pressure. The work chuck 26 includes a solenoid valve (not shown) for switching an adsorbed state and an adsorption released state. As illustrated in FIG. 2, the work chuck 26 is electrically connected to the control unit 70. The solenoid valve (not shown) and the like of the work chuck 26 are controlled based on a control signal supplied from the control unit 70.

As illustrated in FIG. 2, the dividing groove forming device 10 includes a first rotation drive unit 72, a second rotation drive unit 74, a cutter support unit 76, an X-direction drive unit 80, a Y-direction drive unit 82, and a phase adjustment unit 104.

As illustrated in FIG. 2, the first rotation drive unit 72 is a unit for rotationally driving the first cutter 20, and includes the first motor 34 and a first motor driver 84. The first motor 34 of this embodiment is a servo motor and is structured to be rotationally driven at a rotational speed of 8000 to 10000 rev/min. The rotating shaft 34 a of the first motor 34 is provided with a flange 86 to which the first cutter 20 is fixed. The flange 86 is provided with screw holes 88 and the positioning pin 42. The bolts 38 inserted through the through-hole 40 of the first cutter 20 are threadedly engaged with the screw holes 88, respectively. The positioning pin 42 is inserted through the through-hole 44 of the first cutter 20. In a state where the first cutter 20 is fixed to the flange 86, the rotating shaft 34 a of the first motor 34 serves as the rotating shaft of the first cutter 20.

As illustrated in FIG. 2, the first motor 34 is provided with a first phase detection part 90 for detecting the phase of the rotating shaft 34 a (i.e., the phase of the first cutter 20). The first phase detection part 90 of this embodiment includes a rotary encoder. The first phase detection part 90 and the control unit 70 are electrically connected to each other.

The first motor driver 84 illustrated in FIG. 2 supplies a drive current to the first motor 34. The first motor driver 84 is electrically connected to the control unit 70. When the control signal is supplied to the first motor driver 84 from the control unit 70, the first motor driver 84 supplies a drive current corresponding to the control signal to the first motor 34.

As illustrated in FIG. 2, the second rotation drive unit 74 is a unit for rotationally driving the second cutter 22 and includes the second motor 54 and a second motor driver 92. The second motor 54 of this embodiment is a servo motor and is structured to be rotationally driven at a rotational speed of 8000 to 10000 rev/min. The rotating shaft 54 a of the second motor 54 is provided with a flange 94 to which the second cutter 22 is fixed. The flange 94 is provided with screw holes 96 and the positioning pin 62. The bolts 58 inserted through the through-holes 60 of the second cutter 22 are threadedly engaged with the screw holes 96, respectively. The positioning pin 62 is inserted through the through-hole 64 of the second cutter 22. In a state where the second cutter 22 is fixed to the flange 94, the rotating shaft 54 a of the second motor 54 serves as the rotating shaft of the second cutter 22.

As illustrated in FIG. 2, the second motor 54 is provided with a second phase detection part 98 for detecting the phase of the rotating shaft 54 a (i.e., the phase of the second cutter 22). The second phase detection part 98 of this embodiment includes a rotary encoder. The second phase detection part 98 and the control unit 70 are electrically connected to each other.

The second motor driver 92 illustrated in FIG. 2 supplies a drive current to the second motor 54. The second motor driver 92 is electrically connected to the control unit 70. When the control signal is supplied to the second motor driver 92 from the control unit 70, the second motor driver 92 supplies a drive current corresponding to the control signal to the second motor 54.

As illustrated in FIG. 2, the cutter support unit 76 is a unit for supporting the first cutter 20 and the second cutter 22 in such a manner that the first cutter 20 and the second cutter 22 are radially opposed to each other so that rotation axes of the first cutter 20 and the second cutter 22 are parallel to each other. The cutter support unit 76 of this embodiment includes: the first motor 34 to which the first cutter 20 is attached; the second motor 54 to which the second cutter 22 is attached; a Z-direction drive unit 78 for supporting the first motor 34 and the second motor 54; and a fulcrum 102 for supporting the Z-direction drive unit 78. The Z-direction drive unit 78 is a unit for causing the first motor 34 and the second motor 54 to move in the Z-direction, and includes a linear guide and a servo motor (not shown). The Z-direction drive unit 78 is electrically connected to the control unit 70. The servo motor (not shown) and the like of the Z-direction drive unit 78 are controlled based on the control signal supplied from the control unit 70.

The X-direction drive unit 80 illustrated in FIG. 2 is a unit for causing the first cutter 20 and the second cutter 22 to move in the X-direction together with the cutter support unit 76. The Y-direction drive unit 82 illustrated in FIG. 2 is a unit for causing the first cutter 20 and the second cutter 22 to move in the Y-direction together with the cutter support unit 76. Each of the X-direction drive unit 80 and the Y-direction drive unit 82 includes a linear guide and a servo motor (not shown). The X-direction drive unit 80 and the Y-direction drive unit 82 are electrically connected to the control unit 70. The servo motors (not shown) and the like of the X-direction drive unit 80 and the Y-direction drive unit 82 are controlled based on the control signal supplied from the control unit 70.

FIG. 4 is an enlarged front view illustrating a state in which the first rotary blades 32 and the second rotary blades 52 are opposed to each other. The phase adjustment unit 104 illustrated in FIG. 2 is a unit for adjusting the phase of at least one of the first cutter 20 and the second cutter 22 in such a manner that the first rotary blades 32 and the second rotary blades 52 are opposed to each other in an opposing area Q (FIG. 4) in which the first cutter 20 and the second cutter 22 are opposed to each other.

As illustrated in FIG. 2, the phase adjustment unit 104 of this embodiment includes the first motor 34, the first phase detection part 90, the first motor driver 84, the second motor 54, the second phase detection part 98, the second motor driver 92, and the control unit 70. The control unit 70 includes a central processing unit (CPU) that executes various arithmetic processes, and storage devices (ROM, RAM) for storing programs and data. The control unit 70 in the phase adjustment unit 104 controls at least one of the first motor 34 and the second motor 54 for phase adjustment.

A reference line M illustrated in FIG. 4 is a virtual line that is perpendicular to the substrate 12 and passes through the rotation center of the first cutter 20 and the rotation center of the second cutter 22. When the first phase detection part 90 and the second phase detection part 98 output a signal representing an origin position, the tip of each of the first rotary blades 32 and the tip of each of the second rotary blades 52 are disposed on the reference line M in the opposing area Q.

In this embodiment, the plurality of first rotary blades 32 are the same in number as the plurality of second rotary blades 52, and the plurality of first rotary blades 32 and the plurality of second rotary blades 52 are provided at the same pitch angle. Accordingly, the first rotary blades 32 and the second rotary blades 52 can be opposed to each other in the Z-direction in the opposing area Q, as long as the difference between the phase of the first cutter 20 and the phase of the second cutter 22 is equal to an integral multiple of the pitch angle (18 degrees in this embodiment). The control unit 70 illustrated in FIG. 2 controls at least one of the first motor 34 and the second motor 54 in such a manner that the phase difference is equal to an integral multiple of the pitch angle (18 degrees in this embodiment).

[Dividing Groove Forming Method]

When the first dividing groove 14 and the second dividing groove 16 are formed in the substrate 12 along the dividing lines L1 and L2 illustrated in FIG. 3, the substrate 12 is first placed on the rotating table 24 illustrated in FIG. 1, and the substrate 12 is fixed by the work chuck 26. Subsequently, the first dividing groove 14 and the second dividing groove 16 are formed along each dividing line L1 (FIG. 3) by rotationally driving the first cutter 20 and the second cutter 22 to move in the X-direction and the Y-direction.

When the operation for forming the first dividing groove 14 and the second dividing groove 16 along a plurality of dividing lines L1 illustrated in FIG. 3 is completed, the rotating table 24 illustrated in FIG. 1 is rotated to change the direction in which each dividing line L2 (FIG. 3) of the substrate 12 extends, from the Y-direction to the X-direction. After that, the first dividing groove 14 and the second dividing groove 16 are formed along each dividing line L2 (FIG. 3) by moving the first cutter 20 and the second cutter 22 in the X-direction and the Y-direction. Note that an alternate long and two short dashes line illustrated in FIG. 3 indicates the state of the substrate 12 after the direction is changed.

A method for forming the first dividing groove 14 and the second dividing groove 16 along the dividing lines L1 and L2 (dividing groove forming method) will be described in detail below with reference to the flowchart of FIG. 5.

When the control unit 70 illustrated in FIG. 2 starts a dividing groove forming program, the control unit 70 executes steps S1 to S7 illustrated in FIG. 5 in this order. First, in step S1, the control unit 70 controls the first motor 34 and the second motor 54 to rotationally drive the first cutter 20 and the second cutter 22. At this time, the first cutter 20 and the second cutter 22 are separated from each other in the Z-direction by the Z-direction drive unit 78.

During the formation of the first dividing groove 14 and the second dividing groove 16, if the positions of the first rotary blades 32 and the second rotary blades 52 deviate in the X-direction in the opposing area Q illustrated in FIG. 4, a waviness phenomenon occurs on the substrate 12, so that the depth of each of the first dividing groove 14 and the second dividing groove 16 becomes non-uniform. Accordingly, in steps S2 and S3, the control unit 70 of the phase adjustment unit 104 illustrated in FIG. 2, the phase of the second cutter 22 is adjusted in such a manner that the first rotary blades 32 and the second rotary blades 52 are opposed to each other.

Specifically, in step S2, the control unit 70 acquires the phases of the first cutter 20 and the second cutter 22 that are detected by the first phase detection part 90 and the second phase detection part 98 (FIG. 2), respectively. In step S3, the control unit 70 adjusts the phase of the second cutter 22 by controlling the second motor 54 (FIG. 2) in such a manner that the first rotary blades 32 and the second rotary blades 52 are opposed to each other in the opposing area Q (FIG. 4). The control unit 70 continuously performs the processes of steps S2 and S3 until the dividing groove forming program is completed. Note that in step S3, the control unit 70 may control the first motor 34 (FIG. 2) to adjust the phase of the first cutter 20. Further, the control unit 70 may adjust the phases of the first cutter 20 and the second cutter 22 by controlling both the first motor 34 and the second motor 54 (FIG. 2).

In step S4, the control unit 70 controls the X-direction drive unit 80, the Y-direction drive unit 82, and the Z-direction drive unit 78 to thereby position the first cutter 20 and the second cutter 22 to a starting point P1 illustrated in FIG. 3. At this time, the Z-direction drive unit 78 moves the first cutter 20 and the second cutter 22 in directions approaching each other. In step S5, the control unit 70 controls the X-direction drive unit 80 to move the first cutter 20 and the second cutter 22 in the X-direction, thereby forming the first dividing groove 14 and the second dividing groove 16 in the substrate 12.

In step S6, the control unit 70 determines whether or not the first cutter 20 and the second cutter 22 have reached an end point P2 (FIG. 3) in the X-direction. When the control unit 70 determines that the first and second cutters have not reached the end point, the control unit 70 continues the operation of step S5 (movement in the X-direction). When the control unit 70 determines that the first and second cutters have reached the end point, the control unit proceeds to step S7. Whether or not the first cutter 20 and the second cutter 22 have reached the end point P2 can be determined based on, for example, an output of a limit switch (not shown) that is pressed by the cutter support unit 76 (FIG. 2).

In step S7, the control unit 70 controls the X-direction drive unit 80, the Y-direction drive unit 82, and the Z-direction drive unit 78 (FIG. 2), thereby moving the first cutter 20 and the second cutter 22 to the next starting point. Thus, the process for forming the first dividing groove 14 and the second dividing groove 16 along one of the plurality of dividing lines L1 and one of the plurality of dividing lines L2 is finished.

Advantageous Effects of Embodiments

According to this embodiment, the following advantageous effects can be provided by the structure described above. That is, as illustrated in FIG. 4, the first rotary blades 32 and the second rotary blades 52 are opposed to each other in the opposing area Q in which the first cutter 20 and the second cutter 22 are opposed to each other. This structure prevents a waviness phenomenon from occurring on the substrate 12. Accordingly, the first dividing groove 14 and the second dividing groove 16 (FIG. 2) can be formed accurately at a constant depth.

The X-direction drive unit 80 illustrated in FIG. 2 can cause the first cutter 20 and the second cutter 22 to move relatively to the substrate 12. Accordingly, the first dividing groove 14 and the second dividing groove 16 can be smoothly formed. Further, the first motor 34 and the second motor 54 are controlled by the control unit 70. Therefore, the phase of at least one of the first cutter 20 and the second cutter 22 can be adjusted rapidly and accurately.

As illustrated in FIG. 1, the plurality of first rotary blades 32 are the same in number as the plurality of second rotary blades 52, and the plurality of first rotary blades 32 and the plurality of second rotary blades 52 are provided at the same pitch angle. Accordingly, the first rotary blades 32 and the second rotary blades 52 can be easily opposed to each other only by controlling at least one of the first motor 34 and the second motor 54 so that the phase difference is equal to an integral multiple of the pitch angle.

Modified Examples

Note that the implementation of the present invention is not limited to the above embodiments and can be modified in various ways without departing from the scope of the present invention. For example, as illustrated in FIG. 3, in the above embodiments, the first cutter 20 and the second cutter 22 are moved in the X-direction relatively to the substrate 12. On the contrary, the substrate 12 may be moved (not shown) in the X-direction relatively to the first cutter 20 and the second cutter 22.

Further, as illustrated in FIG. 2, in the above embodiments, the phase adjustment unit 104 including the control unit 70 is used as a phase adjustment unit for adjusting the phase of at least one of the first cutter 20 and the second cutter 22. Alternatively, a mechanical phase adjustment unit (not shown) composed of a gear, a timing belt, or the like may be used.

DESCRIPTION OF REFERENCE SIGNS

-   10 Dividing groove forming device -   20 First cutter -   22 Second cutter -   32 First rotary blade -   52 Second rotary blade -   72 First rotation drive unit -   74 Second rotation drive unit -   76 Cutter support unit -   104 Phase adjustment unit 

The invention claimed is:
 1. A dividing groove forming method for simultaneously forming a first dividing groove and a second dividing groove for dividing a substrate at corresponding positions on one surface and the other surface of the substrate, the dividing groove forming method comprising: (a) arranging a first cutter for forming the first dividing groove and a second cutter for forming the second dividing groove in such a manner that the first cutter and the second cutter are radially opposed to each other so that rotation axes of the first cutter and the second cutter are parallel to each other, the first cutter including a plurality of first rotary blades, the second cutter including a plurality of second rotary blades; (b) rotating the first cutter and the second cutter in such a manner that the first rotary blades and the second rotary blades are opposed to each other in an opposing area in which the first cutter and the second cutter are opposed to each other; and (c) forming the first dividing groove and the second dividing groove by causing the first cutter and the second cutter to move relatively to the substrate in a direction in which the first dividing groove and the second dividing groove extend, wherein the plurality of first rotary blades are the same in number as the plurality of second rotary blades, and the plurality of first rotary blades and the plurality of second rotary blades are provided at same pitch angle, said (b) rotating the first cutter and the second cutter comprises: detecting a phase of each of the first cutter and the second cutter; and controlling at least one selected from a group consisting of a first motor for rotating the first cutter and a second motor for rotating the second cutter, in such a manner that a difference between the phase of the first cutter and the phase of the second cutter is equal to an integral multiple of the pitch angle.
 2. A dividing groove forming device for simultaneously forming a first dividing groove and a second dividing groove for dividing a substrate, the first dividing groove and the second dividing groove being respectively formed at corresponding positions on one surface and the other surface of the substrate, the dividing groove forming device comprising: a first cutter for forming the first dividing groove, the first cutter including a plurality of first rotary blades; a second cutter for forming the second dividing groove, the second cutter including a plurality of second rotary blades; a first rotation drive unit for rotationally driving the first cutter; a second rotation drive unit for rotationally driving the second cutter; a cutter support unit for supporting the first cutter and the second cutter in such a manner that the first cutter and the second cutter are radially opposed to each other so that rotation axes of the first cutter and the second cutter are parallel to each other; and a phase adjustment unit for adjusting a phase of at least one selected from a group consisting of the first cutter and the second cutter, in such a manner that the first rotary blades and the second rotary blades are opposed to each other in an opposing area in which the first cutter and the second cutter are opposed to each other, wherein the first rotation drive unit includes a first motor, the second rotation drive unit includes a second motor, the phase adjustment unit includes a control unit for controlling at least one selected from a group consisting of the first motor and the second motor, the plurality of first rotary blades are the same in number as the plurality of second rotary blades, and the plurality of first rotary blades and the plurality of second rotary blades are provided at same pitch angle, the phase adjustment unit includes a phase detection part for detecting a phase of each of the first cutter and the second cutter, and the control unit controls at least one selected from the group consisting of the first motor and the second motor, in such a manner that a difference between the phase of the first cutter and the phase of the second cutter is equal to an integral multiple of the pitch angle.
 3. The dividing groove forming device according to claim 2, further comprising an X-direction drive unit for causing the first cutter and the second cutter to move relatively to the substrate in a direction in which the first dividing groove and the second dividing groove extend. 